Photoelastic analysis of mechanical stresses

摘要

A communication system, such as a portable telephone telepoint system, comprises a handset 11 and a base station 10, the handset can receive a registration sequence from the base station and store a number dependent thereon. The base station meters charge units and generates a new registration sequence when a unit is to be charged and transmits the new sequence to the handset. A new number stored in the handset and dependent on the new sequence differs from the old number to reflect deduction of pre-paid charge units. The handset may display remaining credit information. A voice prompt may warn that credit is running low. IMAGE